DUAL TLR2/7-LIGANDS INDUCE Th1-BIASED IMMUNE RESPONSES AND DISPLAY REDUCED CAPACITY TO ACTIVATE MAST CELLS

LAIÑO, JONATHAN; WANGORSCH, ANDREA; FLACZYK, ADAM; TSAI, MINDY; GALLI, STEPHEN; VIETHS, STEFAN; SCHEURER, STEPHAN; TODA, MASAKO; SCHÜLKE, STEFAN

Ronneburg

Jornada; Paul-Ehrlich-Institut Retreat on Biomedical Research 2017; 2017

Paul-Ehrlich-Institut

Background: TLR-ligands can induce Th1-biased immune responses mimicking the potent immune stimulatory capacity of viruses and bacteria. Aim: To evaluate the immune modulatory capacity of single and dual TLR2/7-ligands in vitro. Methods: Three different TLR2/7-ligands CL401, CL413 and CL531, combining the two single ligands TLR7-ligand 9-benzyl-8-hydroxyadenine (CL264) and TLR2-ligand Pam2CysK4 into novel dual TLR2/7-ligands were evaluated. The immunemodulatory capacity of equimolar amounts of both ligands alone, as a mixture, or as dual TLR2/7-ligands were tested in bone marrow-derived mouse dendritic cells (BMDC), BMDC:T cell co-cultures, and a mouse mast cell line C57.1. Results: In vitro studies revealed that only dual TLR2/7-ligands, CL413 and CL531, induced 11.3- (CL413) and 9.1-fold (CL531) higher IL-10 secretion from BMDC compared to the mixture of both single ligands, and suppressed IL-5, IL-17A and IL-13 secretion induced by OVA from OVA- specific DO11:10 CD4+ T cells. In contrast to this, CL401 induced significant less IL-10 secretion, but stimulated 5.5-fold higher IL-17A production from BMDC:T cell co-cultures compared to CL413 and CL531. All dual TLR2/7-ligands dose dependently suppressed DNP-induced Ag-specific degranulation in C57.1 cells . Interestingly, TLR2- and TLR7-ligands alone or as a mixture did not show comparable immunemodulating effects in vitro. Conclusion: Based on in vitro results, dual TLR2/7-ligands have a promising application as adjuvants in allergy treatment, mainly CL413 and CL531, by modulating pro- and anti-inflammatory cytokines, mast cell degranulation and IL-13 important to induce IgE secretion. Outlook: Ongoing work will investigate the potential use of these dual TLR2/7-ligands to prevent allergic sensitization in a mouse model of intestinal inflammation as well as their ability to activate human dendritic cells.